There are lots of options for optical cabling (e.g. cheap plastic fibers vs. glass fibers) and all have different tradeoffs, e.g. available bandwidth vs. cost.

There are lots of options for optical cabling (e.g. cheap plastic fibers vs. glass fibers) and all have different tradeoffs, e.g. available bandwidth vs. cost. However from what I've seen basically all options are more expensive then equivalent electrical connections (we use both optical and electrical networks in cars). A major advantage of optical is that there are no EMV problems and that you are electrically decoupled (e.g. no hum loops). This might be one of the reasons why toslink is optical. For displays ground loops are typically no problem compared to amplifiers/speakers.